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dma-mapping: add a dma_addressing_limited helper 

This helper returns if the device has issues addressing all present
memory in the system.

Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2019-07-16 21:59:11 +02:00
parent 9087c37584
commit b866455423
1 changed files with 14 additions and 0 deletions
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14
include/linux/dma-mapping.h
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@ -679,6 +679,20 @@ static inline int dma_coerce_mask_and_coherent(struct device *dev, u64 mask)
return dma_set_mask_and_coherent(dev, mask); return dma_set_mask_and_coherent(dev, mask);
} }
/**
* dma_addressing_limited - return if the device is addressing limited
* @dev: device to check
*
* Return %true if the devices DMA mask is too small to address all memory in
* the system, else %false. Lack of addressing bits is the prime reason for
* bounce buffering, but might not be the only one.
*/
static inline bool dma_addressing_limited(struct device *dev)
{
return min_not_zero(*dev->dma_mask, dev->bus_dma_mask) <
dma_get_required_mask(dev);
}
#ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS
void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
const struct iommu_ops *iommu, bool coherent); const struct iommu_ops *iommu, bool coherent);